# How to draw vector with vector field?

Hayat shared this question 1 month ago

Pls see attached in the vector field (x-y plane) i want any arbitrary vector (can change length and direction) along with at that position of field vector. Both are connected tail to tail . 1

I think:

From a named vector you can ask the tail with Point(<vector>,0)

But from a vector in a list this is not possible (maybe a bug)

So it's not possible to write something like:

Vector(Point(<vectorlist>(n), 0), Point(<vectorlist>(n), 0) + <vector>)

In the cases with vectorlists you must have separates lists for tails and vectors

see attached file (correct version now):

• l0 are your old vectors
• l1 are the tails
• l2 are the vectors as in l0 but (new) based on l1
• l3 is what you want (one more vector at tail of all vectors in l2) 1

Hello rami, Hope you are fine. I can not move vector at which field vector is attached it is fixed also how can i change length and direction of my vector. 1

Rami i want just one vector (vector = v) on (xy-plane) which i can change length and orientation and it should be free to move all over the plane. At the tail of v vector Field vector at that point is attached. As i move vector v the field vector changes as per their function.

Also i want to drop perpendicular vector drop from vector v to field vector (this is my new third vector) 1

Sorry, use the correct version (download again)

This is only an example (not what you ask in your last post)

Note the InputBox top in Graphic1 1

My vector v also sit on x-y plane. Because gradient (Field )and vector (v) should have same dimensions.

Vector v = x i +y j

x i = x-component and y-component . and by manually tail of vector can be drag.  1

maybe this 1

use version C: here Vector(v) is correct 1

Hi rami, My project matches the with your B-version attachment. But problem is that One vector should follow the vector field as position changes and second vector is completely my choice what ever length i and direction i choose in term of V = x i + y j

Here change in arbitrary vector also change both vectors. and not any one vector follow field at that point. 1

OK?

If not OK: talk from: any, u_{any Scaled}, u_x and w_{from l2} in my version D 1

Thanks rami . i want not u_x except . Pls see attached.

u.v = v.w = Projection of u into w = projection of w into u = Drop perpendicular of u to the w = Drop perpendicular w to the v = Dot product of u.w

These all represent the same thing.

Drop 90 degree perpendicular vector of u to w (and w to v) and draw vector to from tail to where perpendicular drop. 1

Sorry I don't understand what you want.

But I think you see with the samples above many possibilities how you can do what you really want.

If you have more specific questions please oben a new thread. 1

i just want to drop perpendicular (90 degree) vector from u into w. and make another vector from tail of the w and where where perpendicular vector intersect. 1

Hayat

You have two vectors u and v which are attached to a point which I will call A. You want to resolve u into rectangular components w and e, where e has the same direction as vector v. The following solution which is in terms of u, v and A only, attaches the tail of vector e to point A. Vector w extends from the head of vector e to the head of vector u. The

w=Vector((A+u+Reflect(A+u,Line(A,u))/2,A+u)

e=Vector(A, Translate(A, Vector(u-w)))

The file explains the derivation. 